In recent years, data tracks (hereinafter referred to as “tracks” in some cases) are provided at density ever increasing on a disk used, as recording medium, in the disk storage apparatuses such as hard disk drives (HDDs). The space between any adjacent tracks has therefore decreased. As a result, when a signal magnetically recorded on a track is read, it may be interfered with a signal magnetically recorded on any adjacent track. Such interference between the signals recorded on an adjacent track is sometimes called inter-track interference (ITI).
Because of the ITI, a signal read from a track may not be correctly decoded to reproduce data in some cases. In order to cancel the ITI, techniques have been developed to perform an ITI cancellation process, thereby to remove the interfering component of the signal recorded on the adjacent from the signal read from the track.
In most cases, the ITI cancellation process is performed in units of windows, each having a length less than or equal to, for example, one sector, in order to reduce the influence of frequency fluctuations. The window is a unit by which to detect those parts of reproduced data (bit string) which should be subjected to the ITI cancellation. As the window size decreases from one-sector length (for example, 4000 bits or more), the cancellation coefficient (or cancellation weight) will more likely deviate from the optimal value, as confirmed in the art. Consequently, the ITI may not be cancelled as much as desired.